Device for the control of the vacuum

ABSTRACT

The invention refers to a device to regulate the dosage of fuel, to be used in engine feeding systems by suction of the fuel. The device is to be set in the main conduit of air, overlays the diffuser (7) and involves a set of laminar elements (1) displayed in a radial way according to a common plan, being the fastening of its peripheral extremities achieved by means of its insertion in a double ring (2) which bears a central shutter through narrow radial extensions (6). The ring is fixed to a supporting base with saliences (4) to overcome the spaces between the laminar elements and reenterings (5) to allow its flexure. The flexure of the laminar elements is performed through a calculated progression according to a proper gradient resulting into the formation of in-between spaces (3). Countering the increase of the speed of the current of air, a calculated increase in the area of the sections of the in-between spaces, allow to obtain the regulation of a value of vacuum in the area surrounding the diffuser, vacuum which, in its turn, will determine a debt of fuel proportional to the volume of the current of air in such a way that a correct dosage of the mixture air/fuel in the whole range of rotation of the engine is achieved.

This application is a 371 of PCT/PT95/00002.

TECHNICAL DOMAIN

This invention concerns complementary arrangements to regulate thedosage of fuel, applied to engine feeding systems by suction of thefuel, in order to obtain a air/fuel ratio of the mixture which willfulfill the conditions for a correct performance of the engines in thewhole range of regimes of rotation.

If we regulate a carburettor of a simple construction to the correctrelation of mixture for a maximum number of rotations, this mixture willbe too poor in what the low regimes are concerned. On the contrary, ifwe choose a relation of mixture suitable for low regimes, this mixturewill be too rich for the maximum number of rotations.

PREVIOUS TECHNIQUE

To minimize these inconvenients, arrangements of complementaryregulation included in the carburettors have been idealized and thesecould shortly and in a generic way be specified in the following typesaccording to the description of Dante Giacosa in his book "EndothermicEngines", Ed. Omega, Barcelona, 14th edition, pages 370/3:

Compensating gauge carburettors (Zenith) where the action of the maingauge, regulated to the suitable dosage in a maximum of rotations, iscorrected through a secondary or compensator gauge which enriches themixture in low regimes.

Carburettors of suplementary air (Krebs-Pallas) where the mixture dosedto low regimes is impoverished to the high regimes through theaspiration of suplementary air, by means of conduits placed under thediffuser.

Carburettors of antagonistic air (Solex-Weber) where the mixture, alsoregulated to low regimes is impoverished in the high regimes by means ofair that, required by the same depression, acts antagonistically to thefuel.

Carburettors of double conduits of air where the main flow of air issubdivided by two conduits of aspiration, acting, one of them, to thelow regimes of rotation and the two of them together to the highregimes.

However the referred arrangements of complementary regulation depend onthe actions of movement which use routes of fuel and air in suplementaryconduits--mechanical elements, as springs and small levers. Theseactions involve an appreciable inertia which prevents or delays thetimely and strict adjustment in order to obtain a well balanced dosagein all the extent of rotation regimes.

Adding to these difficulties, such complementary arrangements areperformed integrating them in the carburettors which increases thecomplexity of its construction.

EXPLANATION OF THE INVENTION

The aim of the invention is to solve these problems by means of a devicewhich regulates the vacuum and which acts directly and immediately inthe main current of air. The active laminar elements which constitutethe essential point of the device have a very weak inertia and thischaracteristic allows them to react in an almost instantaneous way tothe changes of the regime of rotation by flexing variably according tothe changes of speed in the main current of air.

From the variation of the amplitude of the bending of the laminarelements results the formation between them of an in-between space aimedat the passage of the current of air, whose area is of variable sizeaccording to the variation of speed of the current of air and accordingto the resistence to the flexure selected for the laminar elements.

An important advantage of the invention stays in the possibility ofmutual adjustment of the mentioned variables in such a way that, fromit, it results, in the space of the conduit that surrounds the diffuserof fuel, the regulation of a certain value of vacuum which, inassociation with a proper value of the gauge which gives fuel to thediffuser allows to obtain a correct dosage in the whole range ofrotation with special incidence to the high regimes.

Another important advantage is the fact that each device and eachcarburettor constitute independent units simplifying its modulation andallowing a functional construction of accurate exactitude.

One of the ways by which the invention can be build up is found next, indetail, with a reference to the drawings which only represent one way ofmaking it.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 displays a view of the device whose laminar elements (1) arekeeping a flat form because they have not been pushed yet by the currentof air to some angle of flexure.

FIG. 2 displays a cross-section of the device inserted in the entranceof the main current of air, overlaying the diffuser, and also shows thecurvilinear shape of each support (5) which shapes the flexure of eachlaminar element.

FIG. 3 displays a view of the device where the laminar elements aretotally flected allowing the formation of an in-between space with itsmaximum value of the area (3).

FIG. 4 displays a cross-section of the profile of the central shutter(6), the complete bend of the laminar elements together with the profileof the respective supports and shows the in-between space for thepassage of the current of air corresponding to the maximum rotation.

As one can notice from the drawings, an example of the device accordingto the present invention is constituted by a set of laminar elements (1)displayed in a radial form following one only plan, being the fasteningof its peripheral extremities done by means of its insertion in a doublering (2) which also bears a shutter in central position (6) throughnarrow radial extensions.

Each laminar element is constituted by a small rectangle of steel bladewith a thickness and corresponding resistance to the flexure calculatedin such a way that it can be flected in its maximum curvature whenpressed by the current of air at its maximum speed.

The set of the laminar elements is fixed to a bearing base, having, thisone, saliences (4) and recesses (5) the saliences being for the purposeof closing the radial spaces which were left free between the laminarelements and the recesses having a depth surface profiled with amodelled curvature which allows the progressive settling of the elementsaccording to a gradient of flexure calculated for a range of rotations.

The central shutter (6) is an element with a static position whoseprofile is modelled in order to contribute, together with the gradientof the flexure of the laminar elements to the formation of thein-between spaces of progressive area.

When the rotation is minimum, the strength of the current of air doesnot allow enough pressure to flect the laminar elements (FIGS. 1 and 2).As the engine rotation increases, also increases the strength of thecurrent of air and consequently increases the flexure of the laminarelements resulting from this an increase of the in-between area too(FIGS. 3 and 4).

This increase of the in-between area following a calculated progressionaccording to an adequate gradient, countering to the increase of thespeed of the air, determines the regularization of a vacuum value in thearea surrounding the diffuser, this value of vacuum, on its turn,determining a flow of fuel which is proportional to the volume of thecurrent of the air and so equivalent to a correct dosage of the mixtureair/fuel.

The use of this invention to engine feeding systems by suction of thefuel will prevent the excess of consumption mainly in the high regimesof rotation, preventing consequently major pollution of the environment.

We claim:
 1. A device to regulate a vacuum applied in engine feedingsystems, comprising a set of laminar elements placed in a mainsuction-air passage, said elements being bendable to change a passageopening area in accordance with variations in an air current, whereinsaid laminar elements (1) are distributed in a radial way in a commonplan, with outer peripheral extremities fastened by insertion in adouble ring (2), one having narrow radial extensions which bears acentral shutter (6) and wherein said double ring is mounted in a bearingbase which is modelled in such a way as to cooperate with said laminarelements in the guild up of a flexure gradient of said laminar elements.2. A device to regulate said vacuum, according to claim 1, wherein saidbearing base comprises saliences (4) and recesses (5), said saliencesfills in radial spaces between said laminar elements and said recessesto cooperate in the build up of a calculated flexure gradient of saidlaminar elements.
 3. A device to regulate said vacuum, according toclaim 1, wherein said laminar elements comprise segments of a steelblade, said blade having a thickness and a corresponding resistance to aflexure calculated in such a way that, while bending, they follow abottom surface of corresponding recesses of a bearing base, inaccordance with changes in pressure of the air flow, caused by a changein angular velocity of an engine.
 4. A device to regulate said vacuum,according to claim 3, wherein said recesses have a bottom surface with acurvilinear profile modeled in order to cooperate in the build up of acalculated flexure gradient of said corresponding laminar element whileallowing its gradual settling, avoiding cumulative vibrations andextemporaneous rupture.
 5. A device to regulate said vacuum, accordingto claim 4 wherein said flexure of the laminar elements is doneaccording to a calculated progression resulting from this gradualflexure, the formation of in-between spaces (3) where an area ofrespective sections varies according to a certain gradient, proportionalto a volume of a current of air.
 6. A device to regulate said vacuum,according to claim 5, further comprising a central shutter with aprofile in accordance with a gradient calculated for a variation offormation of in-between spaces.
 7. A device to regulate said vacuum,according to claim 6, wherein countering to each increase of speed ofsaid current of air, a calculated increase of said area of said sectionsof said in-between spaces allow a regularization of a value of vacuum inan area that surrounds a diffuser (7), said vacuum determines a debt offuel proportional to said volume of the current of air in such a waythat a correct dosage of a mixture air/fuel, in a whole range ofrotation of said engine, is achieved.